A seat angle adjuster is used to connect a seat base with a seat back of an automobile seat so as to improve the comfort of the seat. Passengers can adjust an angle of the seat back to be in an optimum position via the seat angle adjuster so as to achieve the most comfortable and accustomed sitting angle. The driver can adjust the angle of the seat back to obtain the best view so as to facilitate controlling manipulation components such as a steering wheel, a pedal or a gear lever.
With the development of the automobile industry and the gradually increased requirements of the customers, higher demands are imposed on the high strength and the high energy absorption performance of the automobile seat. It also needs to improve the strength and the energy absorption performance of the seat angle adjustment device as one of core members of the automobile seat, so as to effectively protect the passengers during a rearward or forward collision to the automobile.
Particularly, for an individual seat with a safety-belt anchoring point located on the seat back, such as a military vehicle seat, a bus seat, an off-road vehicle seat, a commercial vehicle seat, since the vehicle body of such vehicle is relatively high and wide, the safety-belt anchoring point can not be directly mounted on the vehicle body, but has to be mounted at a top end portion of the seat back. It is well known that, when a car experiences a frontal impact, an impact acceleration applied to the passengers may generally reach 16 g to 35 g (according to the National Automobile Forward Collision Impact Test Standard). Apparently, the requirement for the strength and energy absorption performance of the seat angle adjustment device with the safety-belt anchoring point located at the seat back is even higher.
Reference is made to FIG. 1, which is a schematic view showing the structure of a typical seat angle adjustment device with a ratchet wheel slider structure in a locked state.
As shown in FIG. 1, a slider 1 in this solution has two self-locking surfaces 11, 12, and a locking cam 2 also has two self-locking surfaces 21, 22 respectively corresponding to the two self-locking surfaces 11, 12 of the slider 1. When the seat angle adjustment device is in a normal locked state, the two self-locking surfaces 11, 12 of the slider 1 come into contact with the two self-locking surfaces 21, 22 of the locking cam 2 respectively to form a self-lock; and the two self-locking surfaces 11, 12 are located at two sides of a normal line of the slider 1. In a case that the seat back is loaded, since the self-locking surfaces 11, 12 are located at two sides of the normal line of the slider 1 respectively, both of the two self-locking surfaces 11, 12 support the slider 1 at the same time when a ratchet wheel 4 is subjected to a force (i.e. the seat back is subjected to a force), thus forming a two-point locking, which may effectively prevent the slider 1 from inclining, and ensure an appropriate number of engaged teeth between a toothed part 13 of the slider 1 and a toothed part 41 of the ratchet wheel 4, thereby ensuring the strength of the adjustment device.
However, such seat angle adjustment device only has a one-level strength, that is, when the slider 1 and the ratchet wheel 4 are damaged due to the force applied therebetween reaches a certain extent, the seat back will be toppled. Therefore, such angle adjustment device can only meet the requirement of a normal automobile seat that is not a seat with a safety-belt anchoring point located on a seat back.
For solving the above problem of the seat angle adjustment device having the one-level strength, a seat angle adjustment device having a two-level strength is disclosed in a Chinese patent application Publication No. CN1264655. Reference is made to FIG. 2, which is a schematic view showing an overall structure of the seat angle adjustment device.
The seat angle adjustment device shown in FIG. 2 is in a normal locked state, teeth of a slider 11 engage with teeth of a ratchet wheel 8, a self-locking surface of a locking cam 16 abuts against a self-locking surface of the slider 11 to form a self-clock, and the slider 11 is unslidable in a slide groove of a stop plate 5. In this state, teeth of a pawl 25 are disengaged from the teeth of the ratchet wheel 8. When the device is subjected to a relatively large load, since the teeth of the ratchet wheel 8 engage with the teeth of the slider 11, the ratchet wheel 8 may drive the slider 11 to move, and a side edge of the slide groove of the stop plate 5 may be extruded by a side edge of the slider 11 to be deformed, thus a protrusion 14, forming the slide groove, on the stop plate 5 will be pressed to move, and then the pawl 25 is pushed by the other side edge of the protrusion 14 outwards until the teeth of the pawl 25 is engaged with the teeth of the ratchet wheel 8. Reference is made to FIG. 3, which is a schematic view showing a rotating mechanism of a vehicle after an accident.
In the above process of force loading, it is under a first-level strength in an initial state of force loading, and it is under a second-level strength when the pawl 25 is engaged with the ratchet wheel 8 after the loaded force reaches a certain extent. However, when the second-level strength is enabled, the pawl 25 is pushed to engage with the ratchet wheel by the deformed protrusion 14 of the stop plate 5, thus the manufacturing precision of each part will affect the reliable engagement between the pawl and the ratchet wheel which are in a disengaged state, and affect the energy absorption performance when the car is subjected to an impact, and further affect the use security and reliability. Meanwhile, there are inevitable performance differences between materials in different batches, and materials with different mechanical performances have different degrees and tendencies of deformation, therefore, this solution also has high requirements for the mechanical performances of materials.
In view of this, it is desired to optimize the seat angle adjustment device so as to solve the above defects in the prior art.